Distinguishing Between Serious Vision Impairment and Normal Aging Change
By Eleanor E. Faye, MD
The tendency of older adults (and their families) is to blame vision
changes on aging, but only a comprehensive eye examination can separate
a serious vision impairment from "normal" aging changes. "Normal aging"
of the eye is a term used for decreased visual function unrelated to
ocular disease. Individual visual functions do not decrease at the
same rate, and aging does not inevitably result in disease.
Although the major eye diseases such as cataract, macular degeneration, glaucoma and diabetic retinopathy
are considered to be age related, age is not the only risk factor;
these diseases may occur in children and younger adults as well (Marmor
1995). General health, medications, diet, environmental exposure to
toxins and genetics may modify the course.
Determining Factors That Affect Vision
There
are many physiological changes in eye tissues that minimally affect
visual performance; conversely, there also are eye diseases that do not
initially cause a significant level of dysfunction. Since aging does
not affect all people or all systems uniformly or equally, it is
important to differentiate between normal aging and pathology. A simple
first step in revealing potential problems can be a self-administered questionnaire that identifies functional changes in the individual's sight.
The
eye has seven functions that normally interact smoothly to transmit a
clear image to the brain: visual acuity (the ability to see detail);
the visual field(the horizontal and vertical diameter of the area seen
binocularly in straight ahead gaze); accommodation (ability of the lens
to become more convex to accommodate to near-range tasks); color (the
response of pigments in the cones to combinations of wavelengths of
blue, red and yellow light); adaptation to light and dark, as a
function of the rods and cones; contrast sensitivity (a retinal process
that transmits high to low frequency signals to the brain); and depth
perception.
Diagnosis and treatment are traditionally in the realm of the ophthalmologist or optometrist, yet symptons and their functional implications can be evaluated by any profesisonal involved in the care of the aging person and led to a timely refrerral for diagnosis, treatment and rehabilitation.
Eleanor E. Faye, MD, FACS is the Ophthalmological Advisor, Center for Education, Lighthouse International, New York, NY.
Reproduced with the permission of Oxford University Press from Evans (2001) Oxford Textbook of Geriatric Medicine.
References:
Carter, J.H. (1982). The effects of aging on selected visual functions: color, vision, glare sensitivity, field of vision, and accommodation. In Aging and human visual function (ed. R. Sekuler, D. Kline, and K. Dismukes), pp. 124-9. A.R. Liss, New York.
Cohen, J.M. (1993). Illumination, contrast and glare: problems in poor vision. Practical Optometry, 4, 60-6.
Marmor, M. (1995). Normal age-related vision changes and their effects on vision. In The aging eye and low vision (ed. E.E. Faye and C.S. Stuen), p. 8-10. The Lighthouse Inc., New York.
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